DIY Powerwall 2 – Cell Charger

Diffulty level: Intro – Easy – Intermediate – Expert

Dear fellow battery enthousiast,

Last time we went over the basics of cell charging. This time, we will build charging stations.

Tools needed: Pliers, solder iron.

Hardware needed: Copper, TP4056, 18650 holder, a piece of plywood and glue.

The total BOM costs less than 20$ if you don’t need a power supply, a 5V – 20A fanless PS costs around 20$

Building a 16p charging station:

In my previous article I promised to built a charging station. Today it’s a hands-on write up. Check your scrap bin for some 1,5mm copper wire. (16AWG or 14AWG). Cut 16 pieces of 110mm (4-1/4″) copper wire and 16 pieces of 18mm (3/4″).

Bend the 110mm around the 18650 holder like you can see on the picture. Once all wires are bent, put them aside.

Put some solder on the TP4056 where we will connect the battery and where we will connect the 5V power supply. Do the same thing for the 18650 holder. Bend the pin of the holder 90° and put some solder on it.

When it’s done you can connect the 18650 holder with the TP4056 with the copper pieces. Repeat X times for the number of cells you want to charge at once, in this case 16.

Prepare an appropriately sized piece of plywood to hold all your cell holders. Align the 18650 holders and glue them to the plywood.

Next, we need to distribute the 5V to all the TP4056 modules. I made a copper cable with 3×1,5mm (16AWG) copper wire. Put 3 wires in a bench vice and put the other side in a drill. Gently pull the “trigger” and get a result like you see in the picture below. To make soldering easier, clean it with some steel wool.

Prepare 2 x 16 flexible wires for the positive and ground connection between the TP4056 board and the +5V and ground rail of the power supply. Solder the 16 ground wires to the board first, when done, solder them to the copper cable. Do the same for the positive side of the board. Now it really starts looking like a charger board.

The only hardware we missing is a power supply. If you’re seriously into 18650 and you charge them indoors I advice to choose a fanless power supply. For this board I didn’t have a fanless power supply, so I choose a computer power supply from my scrap box. It’s not in the scope of this project so wont go in detail on how to prepare, but just remove the unwanted wires and select the ground and +5V (black and red). To start your power supply, you have to connect the green wire to ground.

Connect a few 5V red wires to the upper copper cable. Ground, black goes to the lower cable. I used a big terminal block, a smaller one will do the trick too. Fire up the power supply and enjoy the view. You can start charging batteries.

Reminder, the TP4056 is a cheap and fantastic board. It just doesn’t like reverse polarity. If you insert a battery with the wrong polarity it will release some magic smoke and die in a split second.

Don’t worry if it happens, because of the design you can easily replace the faulty one.

Happy charging, see you in the next expisode.

Franky goes green – http://www.easypowerwall.com

Note: Franky is a valued contributor, however, his advice and opinions are his own.